hard to start hot

[notsobigkahuna]

ok, the stationary idle jet cleaning solved the bad idle problem, but i still have the original troubles

the bug runs pretty well but when the motor is hot from a bit of a run she just fights starting - just won't catch. when dead cold again she'll fire right up

any ideas?

kahuna

[73BuzzBomb]

running too lean, maybe?
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'73 Super
2270 type IV

[uswebers]

[notsobigkahuna]

i have a new coil coming so that can't hurt...

after a little investigation this weekend i have narrowed things down a bit (i think). wehn the bug sits and idles there is lots of gas in the filter, maybe 3/4 full or so. if i go for a run, and stop there will be little or no gas in filter. i ordered a new filter too but could it be that the pump can't keep up? i'm thinking now that the reason it will not start hot is cuz its getting no gas??? turning it over eventally gets fuel to the carb and it will idle fine

k

[bumpin_pumpkin]

it might be a fuel pump problem my friend juniors does the same thing

[gophercat]

Fuel delivery does not change with engine temp- unless you are getting vapor lock in which case the engine would not start after turning for a bit.

The thing you have to consider is that the carb is already full of gas when the car was just run. The filter can be bone dry and the car will start. If it were the filter or fuel delivery it would be a consistant problem and not relate to engine temps unless it is vapor lock occuring which it does not sound like is occuring since the engine does start after cranking a bit while hot.

If not enough fuel was getting to the carb after being run, then when the car is shutdown and sits there how would there be gas in the carb to start it cold? There wouldn't if fuel delivery was the issue. Fuel doesn't get delivered to the carb by letting the engine cool. And when starting it, hot or cold, the fuel is delivered the same. By thinking logically, and with vapor lock being ruled out as the cause, you would have the same startup problem in both cases, hot or cold, if it was fuel delivery related. Also if fuel delivery were the issue the car would run like crap when it gets at higher speeds since the engine would be starving for fuel.

Listen to the original posts. There are several reasons a car will not start when it is hot. The valves need adjusting or the heads may need to be retourqued just a bit. The starter overheats and cannot turn the engine fast enough. The carb is out of adjustment or the timing is incorrect. Also the choke may not be working correctly. If you really want to check fuel delivery then the float level would be another thing to check, but as stated, fuel delivery does not sound like the problem here.

The best way to know everything is working properly is to check. Check the compression to know it is good, don't assume because the car pulls well. Check the valve settings to be sure you aren't losing compression due to the valves being open too long. When setting the valves get it right, if needed- a little loose is better than a little tight.

My guess, like the others, is the valves. When it is cold the valves close all the way. If they are set tight, when the engine gets hot the valves do not close all the way. There is too little compression. The engine will spin freely when trying to turn it over, and with the lower compression build up per stroke it will take longer to fire.

When you are trying to start it, do you push the gas pedal all the way to the floor when you try to start it and then let off when it fires. You should be doing this hot or cold. Opening the throttle gives it a quick prime and allows for more air flow to create greater compression, which is the reason you hold the throttle wide open when doing a compression check.
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1972 super
1974 Standard